Networking reference
TCP & UDP Port Numbers – Service & Protocol Lookup
Search the complete IANA service-name and port-number registry by port, protocol, service, assignee or RFC, including TCP, UDP, SCTP, DCCP and unqualified entries.
| Port | Protocol | Service | Description | Assignee | Registration date | Reference/RFC | Status | Record details |
|---|---|---|---|---|---|---|---|---|
| 497 | UDP | retrospect | Retrospect backup and restore service | Retrospect, Inc. | — | — | Assigned | → |
| 498 | TCP | siam | siam | Philippe Gilbert | — | — | Assigned | → |
| 498 | UDP | siam | siam | Philippe Gilbert | — | — | Assigned | → |
| 499 | TCP | iso-ill | ISO ILL Protocol | Mark H. Needleman | — | — | Assigned | → |
| 499 | UDP | iso-ill | ISO ILL Protocol | Mark H. Needleman | — | — | Assigned | → |
| 500 | TCP | isakmp | isakmp | Mark Schertler | — | — | Assigned | → |
| 500 | UDP | isakmp | isakmp | Mark Schertler | — | — | Assigned | → |
| 501 | TCP | stmf | STMF | Alan Ungar | — | — | Assigned | → |
| 501 | UDP | stmf | STMF | Alan Ungar | — | — | Assigned | → |
| 502 | TCP | mbap | Modbus Application Protocol | modbus.org | — | — | Assigned | → |
| 502 | UDP | mbap | Modbus Application Protocol | modbus.org | — | — | Assigned | → |
| 503 | TCP | intrinsa | Intrinsa | Robert Ford | — | — | Assigned | → |
| 503 | UDP | intrinsa | Intrinsa | Robert Ford | — | — | Assigned | → |
| 504 | TCP | citadel | citadel | Art Cancro | — | — | Assigned | → |
| 504 | UDP | citadel | citadel | Art Cancro | — | — | Assigned | → |
| 505 | TCP | mailbox-lm | mailbox-lm | Beverly Moody | — | — | Assigned | → |
| 505 | UDP | mailbox-lm | mailbox-lm | Beverly Moody | — | — | Assigned | → |
| 506 | TCP | ohimsrv | ohimsrv | Scott Powell | — | — | Assigned | → |
| 506 | UDP | ohimsrv | ohimsrv | Scott Powell | — | — | Assigned | → |
| 507 | TCP | crs | crs | Brad Wright | — | — | Assigned | → |
| 507 | UDP | crs | crs | Brad Wright | — | — | Assigned | → |
| 508 | TCP | xvttp | xvttp | Keith J. Alphonso | — | — | Assigned | → |
| 508 | UDP | xvttp | xvttp | Keith J. Alphonso | — | — | Assigned | → |
| 509 | TCP | snare | snare | Dennis Batchelder | — | — | Assigned | → |
| 509 | UDP | snare | snare | Dennis Batchelder | — | — | Assigned | → |
| 510 | TCP | fcp | FirstClass Protocol | Mike Marshburn | — | — | Assigned | → |
| 510 | UDP | fcp | FirstClass Protocol | Mike Marshburn | — | — | Assigned | → |
| 511 | TCP | passgo | PassGo | John Rainford | — | — | Assigned | → |
| 511 | UDP | passgo | PassGo | John Rainford | — | — | Assigned | → |
| 512 | TCP | exec | remote process execution; authentication performed using passwords and UNIX login names | — | — | — | Assigned | → |
| 512 | UDP | comsat | — | — | — | — | Assigned | → |
| 512 | UDP | biff | used by mail system to notify users of new mail received; currently receives messages only from processes on the same machine | — | — | — | Assigned | → |
| 513 | TCP | login | remote login a la telnet; automatic authentication performed based on priviledged port numbers and distributed data bases which identify "authentication domains" | — | — | — | Assigned | → |
| 513 | UDP | who | maintains data bases showing who's logged in to machines on a local net and the load average of the machine | — | — | — | Assigned | → |
| 514 | TCP | shell | cmd like exec, but automatic authentication is performed as for login server | — | — | — | Assigned | → |
| 514 | UDP | syslog | — | — | — | [RFC5426] | Assigned | → |
| 515 | TCP | printer | spooler | — | — | — | Assigned | → |
| 515 | UDP | printer | spooler | — | — | — | Assigned | → |
| 516 | TCP | videotex | videotex | Daniel Mavrakis | — | — | Assigned | → |
| 516 | UDP | videotex | videotex | Daniel Mavrakis | — | — | Assigned | → |
| 517 | TCP | talk | like tenex link, but across machine - unfortunately, doesn't use link protocol (this is actually just a rendezvous port from which a tcp connection is established) | — | — | — | Assigned | → |
| 517 | UDP | talk | like tenex link, but across machine - unfortunately, doesn't use link protocol (this is actually just a rendezvous port from which a tcp connection is established) | — | — | — | Assigned | → |
| 518 | TCP | ntalk | — | — | — | — | Assigned | → |
| 518 | UDP | ntalk | — | — | — | — | Assigned | → |
| 519 | TCP | utime | unixtime | — | — | — | Assigned | → |
| 519 | UDP | utime | unixtime | — | — | — | Assigned | → |
| 520 | TCP | efs | extended file name server | — | — | — | Assigned | → |
| 520 | UDP | router | local routing process (on site); uses variant of Xerox NS routing information protocol - RIP | — | — | — | Assigned | → |
| 521 | TCP | ripng | ripng | Robert E. Minnear | — | — | Assigned | → |
| 521 | UDP | ripng | ripng | Robert E. Minnear | — | — | Assigned | → |
Look up a port number, service name, transport protocol, assignee or RFC in IANA's current registry. The table keeps every row in the 17 August 2026 snapshot, so one port can appear more than once when it has separate TCP, UDP or other registrations.
How to use the port lookup
Enter a number such as 22, 53, 80, 443, 3306 or 8080 to find exact registrations and any registered range containing that port. You can also search for a service such as ssh or mysql, a protocol, an assignee, or reference text such as RFC9110. Use the Protocol and Status filters when a search returns several rows.
Blank values mean the source registry does not provide that field. They have not been guessed. Assignee identifiers are resolved against the people and organisations directory in IANA's XML registry where a readable name is available.
Port ranges and status labels
- System ports: 0–1023. These are also commonly called well-known ports.
- User ports: 1024–49151. IANA can register services in this range.
- Dynamic or private ports: 49152–65535. IANA does not assign services from this range.
Status is a page-level label derived from the source row. Reserved and Unassigned follow IANA's description. Rows whose source text identifies a de-registration or removal are labelled Deprecated or removed. A row with a service name but no port is labelled Service name only. All other rows are labelled Assigned.
Why the same port can have several entries
TCP and UDP are different transport protocols, so the same number can be registered for both without representing the same network conversation. The registry also includes SCTP, DCCP, aliases, historic records and registrations without a specified transport protocol. They remain in this database so the source is not reduced to a hand-picked list.
Common port questions
What service normally uses port 22?
IANA registers ssh on port 22 for TCP and UDP, with an additional SCTP registration. In everyday networks, TCP port 22 is the familiar SSH remote-access service.
Why does port 53 show TCP and UDP?
The domain service is registered on port 53 for both TCP and UDP. DNS software chooses the transport according to the operation and response requirements.
What is the difference between ports 80 and 443?
IANA associates port 80 with HTTP-related service names and port 443 with HTTPS. A registration describes the conventional use; it does not inspect or guarantee the traffic running there.
What uses port 3306?
The registry lists mysql on port 3306 for TCP and UDP. MySQL client connections are ordinarily associated with TCP, but this page retains both official registry rows.
Is port 8080 always an HTTP proxy?
No. IANA registers http-alt on port 8080 for TCP and UDP, but applications can use ports differently. Identify the listening process and configuration before drawing a security conclusion.
Should I open a port because it is registered here?
No. Open only the ports required by a known application and restrict source networks where possible. A registry entry is not a firewall recommendation.
IANA updates the registry as assignments change. Use Report incorrect data if this snapshot no longer matches the official record, and include the IANA or RFC link so the change can be verified.
Provenance